1. Field of the Invention
This invention relates generally to cable television communication systems. More particularly, the invention relates to a cable television system which determines the quality of data received by settop terminals and utilizes this determination to diagnose system errors without removing the system from service.
2. Description of Related Art
Cable television (CATV) communication networks are being used more frequently for applications that require transmission of data, in addition to analog audio and video information. With the onset of utilizing CATV networks for data-critical applications (such as home banking and shopping) and life-saving applications (such as medical alert and alarm services), transmission of error-free data has become a necessity. Additionally, consumer demand and competition from regional telephone operating companies are forcing all data transmission service providers to provide better quality services.
A primary concern of CATV service providers is the time and costs associated with diagnosing transmission network problems and correcting the problems. Unfortunately, the first indication of a problem within the CATV system is usually the receipt by the CATV network operator of a subscriber complaint. Although a technician may be dispatched to the subscriber's household, the problem may not originate with that particular subscriber's settop terminal. On the contrary, an entire portion of the CATV system may be inoperable. Accordingly, it is difficult for CATV network operators to effectively monitor the operation of the system and to quickly determine the location of problems in order to prevent system-wide failure.
There are known systems that measure different types of interference on a CATV system. One method for measuring the signal-to-noise ratio on a cable television system without taking the system out of service is disclosed in U.S. Pat. No. 5,073,822 (Gamm et al.). This system uses a modified spectrum analyzer for determining signal-to-noise ratios at certain locations within the CATV network. Additionally, U.S. Pat. No. 5,394,185 (Bernard) discloses a technique for utilizing an analyzer to filter out the carrier frequency of the CATV signal and to detect hum caused by the power line and low frequency disturbances. Although both of these systems measure the interference on the CATV transmission network, they do not analyze whether the data received at the settop terminal includes errors. Further, these systems require expensive equipment that would be impractical for a system-wide implementation.
Accordingly, there exists a need for an inexpensive system which accurately detects the error rate of data received by all settop terminals on a CATV network to aid in system diagnostics.